package com.flopbox.client;

/*
 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
import com.flopbox.server.FileInfo;
import java.io.*;
import java.nio.file.*;
import static java.nio.file.StandardWatchEventKinds.*;
import java.util.*;
import java.sql.Date;
 
/**
 * Example to watch a directory (or tree) for changes to files.
 */
 
public class Watcher extends Thread {
    private final WatchService watcher;
    private final Map<WatchKey,Path> keys;
    private boolean trace = false;
    private LinkedList<FolderListener> folderListeners = new LinkedList<>();
    private String dir;
 
    @SuppressWarnings("unchecked")
    static <T> WatchEvent<T> cast(WatchEvent<?> event) {
        return (WatchEvent<T>)event;
    }
 
    /**
     * Register the given directory with the WatchService
     */
    private void register(Path dir) throws IOException {
        WatchKey key = dir.register(watcher, ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY);
        if (trace) {
            Path prev = keys.get(key);
            if (prev == null) {
                System.out.format("register: %s\n", dir);
            } else {
                if (!dir.equals(prev)) {
                    System.out.format("update: %s -> %s\n", prev, dir);
                }
            }
        }
        keys.put(key, dir);
    }
 
    /**
     * Creates a WatchService and registers the given directory
     */
    Watcher(Path dir) throws IOException {
        this.dir=dir.toString();
        this.watcher = FileSystems.getDefault().newWatchService();
        this.keys = new HashMap<>();
        // Create listeners for the selected directory
        register(dir);
 
        // enable trace after initial registration
        this.trace = true;
    }
 
    
    
    
    public void run() {
        for(;;) {
 
            // wait for key to be signalled
            WatchKey key;
            try {
                key = watcher.take();
            } catch (InterruptedException x) {
                return;
            }
 
            Path dir = keys.get(key);
            if (dir == null) {
                System.err.println("WatchKey not recognized!!");
                continue;
            }
 
            for (WatchEvent<?> event: key.pollEvents()) {
                WatchEvent.Kind kind = event.kind();
 
                // TBD - provide example of how OVERFLOW event is handled
                if (kind == OVERFLOW) {
                    continue;
                }
 
                // Context for directory entry event is the file name of entry
                WatchEvent<Path> ev = cast(event);
                Path name = ev.context();
                
                Path child = dir.resolve(name);
                
                // Add to event
                for (FolderListener fl : folderListeners){
                    fl.fileChanged(kind, child);
                }
            }
 
            // reset key and remove from set if directory no longer accessible
            boolean valid = key.reset();
            if (!valid) {
                keys.remove(key);
 
                // all directories are inaccessible
                if (keys.isEmpty()) {
                    break;
                }
            }
        }
    }
    
    public void addFolderListener(FolderListener listener){
        folderListeners.add(listener);
    }
        
    public boolean removeGrannyListener(FolderListener listener){
        return folderListeners.remove(listener);
    }  
 
    public static void main(String[] args) throws IOException {        
        // register directory and process its events
        Path dir = Paths.get(System.getProperty("user.home") + File.separator + "flopBox");
        // Check if path exists
        if (!dir.toFile().isDirectory()) {
            // Create path
            File f = dir.toFile();
            f.mkdir();
        }
        
        new Watcher(dir).run();
    }
    /**
     * This method list all existing files in the watched directory
     * @return Returns a list of FileInfo objects representing the existing files in watches directory
     */
    public ArrayList<FileInfo> listFiles(){
        ArrayList<FileInfo> list=new ArrayList<FileInfo>();
        File folder=new File(this.dir);
        File[] files=folder.listFiles();
        for(File f:files){
            if(f.exists()&&!f.getName().equalsIgnoreCase(".DS_Store")){
                //Constructs and adds a FileInfo instance to the list
                list.add(new FileInfo(new Date(f.lastModified()),f.getName()));
            }
        java.util.Collections.sort(list); 
        }
        return list;
    }
    public String getDir(){
        return this.dir;
    }
}